Apparatus for flame hardening tubular structures



April 14, 1942. c, EMERY ET AL 2,279,564

APPARATUS FOR FLAME HARDENING TUBULAR STRUCTURES Filed Oct, 50, 1959Patented Apr. 14, 3%42 Users" TUBULAR. STRUCTUR Frank C. Emery, LosAngeles, and Edwin F. Green, Lynwood, Calif., asslgnors to AxelsonManufacturing 00., Los Angeles, Calii., a corporation of CaliforniaApplication October so, 1939, Serial nascrsza 8 Claims.

Our invention relates to an apparatus for flame hardening the interior.surfaces of bores.

In many industries it is desired to harden the interior surfaces ofbores on various pieces of machinery and the most effective meanshereto! fore known for accomplishing this result has been to employ acase hardening process which is laborious and expensive and whichprocess frequently leaves the hardened surfaces with scale or coatingsof oxide which must be subsequently removed in order to provide smoothsurfaces, particularly if the bores are to receive other machinery partswhich move within the bores as is the case with engine and pumpcylinders, linings. therefor, sleeves, bushings, and the like.

While it will be understood that our invention is obviously applicableto the treatment of bores in any machine elements or parts regardless oflength and diameter of the bores, our invention is particularly usefulin connection with the manufacture of oil well pumps, wherein the barrelof the pump is usually formed of a relatively long length (up to twentyor more feet) of relatively small bore and thin walled tubing (internaldiameters whichrange upwardly from about one inch and the wall thicknessof which may be It is therefore an object of our invention to provide anapparatus by which bores may have their internal surfaces flame hardenedby a flame hardening process in which a burner may be bodily introducedinto the bore to direct jets of flame against the interior surface ofthe bore and in' which a cooling medium is so introduced ahead of andbehind theflame as to confine the application of heat to the surface tobe hardened the flame hardening of bores inwhich the burner one-eighthof an inch or more). Thes barrels provide the pump cylinder within whichreciprocates a pump plunger which must make sealing contact. It istherefore essential that the internal surface of the barrel be extremelysmooth throughout its length, accurately sized throughout its length andpresent to the reciprocating.

plunger a hard, wear-resistant surface.

Though it is necessary to harden only the interior surface of any suchbores, it is impossible,

when using the case hardening process, to accurately and uniformlycontrol the distribution of heat through all parts of the metalsurrounding the bore to avoid the building up of undesirable internalstresses which, for example in thin walled structures, will result inthe warping of processes, it has been common practice to employ linerswithin the barrel constructed of a plurality of short sections ofaccurately sized tubing to provide the necessary accurately sized andhardened surface for cooperation with the pump plunger.

" is so constructed as to provide a plurality of jets directed radiallyagainst the internal surface of the bore to provide a substantial circleof flame extending about the cross section of the bore and confining theheated area in a direction longitudinal of the bore by cooling mediumwhich is introduced ahead of and behind the flame jets.

Another object of our invention is to provide a burner of the characterdescribed in the preceding paragraph wherein the cooling medium isintroduced through the burner and acts to cool I of the flame jets so'asto produce, in effect, ap'ai of spaced circles of cooling mediumextending across the cross section of the bore and defining the gasessupplied to theburner and to cool the burner itself and thereby avoidflash-backs or pre-ignition of the gases employed to produce the flame.

Another object of "our invention is to provide a burner as described inwhich the cooling medi- J um is ejected' from the burner. as two groupsof spray streams, one group directed rearwardly of the flame jets andthe other directed forward a short zone betweenthem within which theapplication of heat confined.

It is also an object of ourinvention to provide an apparatus ofthecharacter set forth in the preceding paragraph in which means isprovided for rotating the device having the bore to be treated about ahorizontally disposed longituto the surface of the bore is dinal axiswhile the flame is being passed therethrough to permit the use of wateror other liquid cooling medium for both quenching and prevent-.

ing pre-heating.

Another object of our invention is to provide an apparatus as set forthin the preceding paragraph; wherein the cooling medium is introducedinto the rotating bore to be treated as two sepathe interior of thetubing I, being supported upon a supporting tubular structure I. Thetubular supporting structure I may be carried in the tool post upon theconventional lathe carriage but we have found it desirable to substitutea carriage construction 8 which includes a guiding means 9 resting uponways In of the lathe bed II and adapted to he slid therealong. Thecarriage 8 preferably includes a downwardly depending portion l2 whichcarries a means engaging a conventional lathe feed screw [3 so thatrotation of this feed screw will operate to advance the carriage 8 alongthe ways III to cause the burner 6 to pass at a uniform ratelongitudinally through the tubing l.

The carriage 8 is provided with a manifold M into which is secured thetubular supportingstructure The'manifold l4 preferably includes the boreto control the depth to whichthe interior surface of the bore is heatedto the desired temperature.

Itis a still further object of our invention to provide in an apparatusof the character set forth in the preceding paragraphs a means foradjusting the heat of the flame, the rate of travel of the flame throughthe bore, and the rate of flow of cooling medium to the heated portionsof the bore to permit the control of depth to which the surface ishardened, the degree of hardness imparted thereto and the degree oftempering effected upon the hardened portions of the surface.

It is a further object of our invention to provide in an apparatus ofthe character set forth in the preceding paragraph a means forsupporting a burner centrally of the bore as it is passed longitudinallytherethrough.

Other objects and advantages of our invention will be apparent from astudy of the foltails of construction.

Referring to the drawing, we have illustrated in Fig. 1 one form offlame hardening apparatus of our invention which is particularly adaptedto the hardening of the internal surface of a long length, smalldiameter tube such as might be used for pump barrels. This apparatus isillustrated as including a means for supporting a relatively long lengthof small bore tubing I for rotation about its horizontally disposedlongitudinal axis. The means for so holding and rotatting the tubing lis illustrated in Fig. 1 as comprising a conventional engine lathe 2,it'having been found that such a lathe is particularly adapted for thisuse, although it is to be understood that other types of apparatuscapable of performing the desired functions would be equally and 5.

A combination burner and spray head't is mounted for longitudinal axialmovement along a means for adequately mixing in the proper proportionsoxygen, which may be delivered from an oxygen supply tank l5 by means ofa flexible hose l6, and acetylene, or other combustible gas, which maybe obtained from a gas supply tank I! and delivered to the manifold M bymeans of v a flexible hose i8.

Provision is also made in the manifold M for receiving, but keepingseparate from the mixture of oxygen and acetylene, a cooling-medium,such as Water, which may be supplied thereto from a suitable supply 19by means of fluid connections 20 and 2|. A control valve 22 ispreferably interposed between the fluid supply lines 20 and 2| so thatthe rate. of flow of cooling medium may be adjusted. The control valve22 is preferably formed as a small'carriage and includes meanscooperating with the ways ill of the lathe bed.

ll to permit the control valve 22 to slide along these ways. The valvestructure 22 is preferably connected by means of a bar 23, or similarconnecting means, to the carriage 8 so that as the carriage 8 movesalong the lathe bed H the control valve 22 is also caused to movetherealong. The length of the bar 23 is so adjusted as to dispose thecontrol valve 22 adjacent the burner 6 so that an operator disposedadjacent the control valve 22 may observe exteriorly the effects of theburner 6 within the tube l and control the amount of liquid flow interms of what is observed.

We have illustrated in Figs. 2 and 3 the details of construction'of thepreferred form of combination burner and spray head 6 and tubularsupporting structure 1 therefor. The tubular supporting structure Ipreferably comprises a relatively thin walled tubing 24 within which isconcentrically mounted a similar but smaller piece of tubing 25. Thetubing 25 is so connected to the manifold M as to convey to the burner 6the mixture of combustible gases which is received from the supply tanksI5 and H. The annular space between the exterior of the tubing 25 andthe interior of the tubing 24 is connected within the manifold 14 to theliquid supply line 2| so that the cooling medium which is deliveredthereby to the burner 6 surrounds the combustible gas which is containedwithin the tubing portion 25.

The combined burner and spray head 6 preferably includes a guiding orsupporting portion 26 which is provided with an axially extending bore21 adapted to receive the end of the outer tubing 24 and be securedthereto by any suitable means, such as brazing or silver soldering. Theguiding and supporting structure 26 is provided with a pair ofdownwardly and outwardly directed feet Aburner head 3I is secured tothat end of the:' supporting structure 25 which is opposite to that endsecured to the tubing 24. .The burner head 3| is preferably providedwith a large diameter cylindrical portion 32 and a small diametercylindrical portion 33 which'are interconnected by a tapering or conicalsection 34. The enlarged cylindrical portion 32 is prefer-ably machinedso as to provide an internal recess 35 which is" annular' inshape havingan internal boss 35 disposed cen'trally. therein. The annular space 35communicates with the bore 21 provided in the supporting structure 26 sothat cooling medium which is conveyed through the annular space betweenthe tubings 24 and 25 is conducted through the bore 21 and into theannular space 35.

A set of spray openings 31 comprising relatively small bore orifices areprovided in the conical section 34 of the burner head 3| and communicatebetween the cooling medium space 35 and the exterior of the'burner. Eachof the orifices 31 is directed forwardly at an angle to the axis of thetubular support I so that jets of cooling medium 38 which are dischargedtherefrom are projected forwardly and strike the interior surface 38 ofthe tubing I at a point in advance of the forwardend of the burner 8. Asimilar coacting set of orifices 39 is also provided which communicatesbetween the exterior surface of the large diameter cylindrical portion32 and the annular space 35. The orifices 39 are preferably directedrearwardly at an angle to the axis of the tubing I so that jets ofcooling medium 48 discharged therefrom will strike the interior surfaceof the tubing I at a rearwardly directed angle thereto and at a positiondisposed to the rear of the orifices 39.

It will be observed thatas the tubing I is disposed with its axissubstantially horizontal and is being continually rotated about thisaxis by the spindle driving mechanism of the lathe 2 that the jets ofcooling medium 38 which are directed forwardly will impinge upon theinterior surface 38 of the tubing I at a forwardly directed angle so asto operate to force a continuous stream A of the cooling mediumforwardly along the tubing to be discharged out that end which iscarried in the lathe chuck 3. In a similar manner, the cooling mediumwhich is directed against the interior wall 38 of the tubing I by thejets 48 will be forced thereby in a continuous stream B rearwardly alongthe tubing I to be discharged out.

the end thereof which is carried by the-steady rest 5.

It will be apparent that the operation of the sets of jets 38 and 48 isto apply the cooling medium substantially uniformly to the entireinterior surface. of the tubing I with the exception of a relativelyshort cylindrical zone disposed between the zones of application to theinterior surface 38 of the jets 38 and 48. It is against thislongitudinally limited zone of the interior of the tubing I that amultiplicity of individual flame jets M is directed. The flame jets 4|are each preferably disposed substantially normal to the axis of thetubing I, this disposition being obtained by providing a multiplicity ofburner openings 42 which communicate between the exterior'surface of thesmall diametercylinder portion 33 and a longitudinal bore 43 extendingtherethrough. The bore 43 communicates with the interior of the gassupply tubing and extends through the cylindrical boss 36 to which theend of the tubing 25 maybe secured as bybrazing or silver soldering.

The number of openings 42 employed is pref- 'erably made equal to or amultiple of the number of sprayjet openings 31 employed, each of theopenings 42 being disposed in staggered relationship relative toadjacent openings3l so thatthe flame jets 4I arecaused to pass betweenadjacent cooling median jets 38. The extreme forward end of the bore 43may be closed by means of a screw plug "44 threadedly engaged with theforward end of the bore 43 and adapted to clamp a seal or gasket 45against the forward end of the small diameter cylindrical portion 33.The plug 44 is preferably formed with a longitudinally extending boss 46which projects into the bore 43 so that by selecting the diameter andfor gases through the bore and jets 4I may be regulated to produce thedesired throw of the names from the jets as well as to produce a steady,smooth, uniform flow of the gases therefrom. I

In operation, the apparatus is set up in the fashion illustrated in Fig.1, :the proper propertions of oxygen and acetylene or other combustiblegas are provided in the burner 8 and the burner ignited to provide theflame jets M. A flow of cooling medium is then started by means of thefluid control 'valve 22 and the tubing I is rotated and the feed screwI3 engaged to cause the carriage 8 to advance to the left, asillustrated in Fig. 1, and cause the burner 6 to enter and pass throughthe interior of the tubing I. As the burner 6 passes through the tubing,the cooling medium supplied by the jets 38 operates to'cool the portionsof the tube which are disposed ahead of the flame jets 4| to prevent preheating of the tube either by conduction through the metal or by the hotgases resulting from the combustion of the gases-supplied to theburner.-

It will be observed that as the burner 6 is ad vanced through thetubing, the flame jets 4| operate to heat that zone which lies betweenthe two zones of application of the cooling medium flame jets 4I andoperate to quench these heated I portions and harden the interiorsurface of the tubing in a well known manner. The cooling medium whichis forcedout the rear end of the tube by the jets 48 operates tocontinually cool the hardened portions of the tube to prevent annealingor tempering of these portions. It has been found, however, that if therate of flow of cooling medium is properly controlled the hardenedportions of the tubing'may be reheated by conduction from the heatedzone-toprovide a tempering of thesehardened portions. It will beobserved that the amount of tempering which is provided may be readilycontrolled by controlling the rate of flow of the cooling medium to theburner.

Attention is also called to the fact that the depth to which the wallsof 'the tubing l are heated to a temperature in excess of. the criticaltemperature depends upon the rate of gas flow to the burner 6 and therate at which the burner is moved through the tubing, while the degreeof hardness is dependent upon the severity of the body for withstandingshocks and impact loads.

Byemploying a burner of the character described herein by which thecooling medium surrounds the supply pipe leading to the burner and alsocomes into intimate contact with the burner, the combustible gas mixtureand the burner are maintained at such low temperatures as to :preventflash-backs and our burner can be successfully employed within tubes orbores having diameters in the order of one inch or less.

.It has been found that an operator, by experience, may observe andrecognize the operating conditions as regards the depth to which thehardening of the tubing is carried and the degree of hardness thereof byobserving 'the exterior of the tubing at the location of the flame 4|within the tubing. It accordingly lies within the interior surface .ofsaid bore to heat a short cy-v lindrical zone to a temperature in excessof the critical temperature; means associated with said burner fordirecting a cooling medium against said interior and about the .entireperiphery burner; and means associated with said burner for directing acooling medium against said interior surface after it is heated toquench and harden said heated surface.

scope of this invention to centralize all of the poses of illustration,specifically described herein,

it will be understood by thoseskilled in this art that the principles ofour invention may be readily employed for the flame hardening of theinterior surfaces of other types of bores and for the effectivetreatment of other types of machinery in which the same problems are:presented, and

we, therefore, do not desire to be limited to any of the detailsillustrated and described herein,

except as defined in the appended claims.

We claim:. 1. In an apparatus for hardening the interior surfaces ofbores in machine elements, the combination of: a burner; means foradvancing said burner longitudinally through said bore; means on saidburner for heating the interior surface of said bore to a temperature inexcess of the critical temperature; and means associated with saidburner for applying a cooling medium to said element within said bore onopposite sides of said burner to confine the heat to a short cylindricalzone and to quench and to harden the surface immediately after it isheated.

2. In an apparatus for hardening the interior surface of bores inmachine elements, the combination of: a burner; means for advancing saidburner longitudinally through said bore; means on said burneriordirecting flame against the 3. In an apparatus for hardening theinterior of bores in machine elements, the combination of: means forrotating said element about the longitudinal axis of said bore disposedhorizontally;

a burner; means for advancing said burner longitudinally through saidbore while said element is rotating; means for conveying a flameproducing combustible mixture to said burner; means on said burner fordirecting flame against the interior surface of said bore to heat ashort cylindrical zone to a temperature in excess of the criticaltemperature; and means associated with said burner for confining thehe'atingeffect of said flame to said zone comprising means for directinga cooling medium against said interior surface and forwardly in advanceof said zone; and means for directing a cooling medium against saidinterior surface immediately after it is heated to quench and harden theheated surface.

4. In an apparatus for hardening the interior surface of bores inmachine elements, the comed surface immediately after. it is heated toquench and harden said surface; a conduit for conducting said coolingmedium to the location of said burner; valve means in said conduit forcontrolling the amount of cooling medium conveyed to said burner tocontrol the severity of the quench; and means mounting said valve meansfor movement with said burner exteriorly of the b'ore along the side ofsaid element.

5. In a burner for use in flame hardening the interior of bores, thecombination of: a head insertable in said bore for advancing movementlongitudinally. therethrough; a gas passage in said head, a plurality ofoutwardly directed burner openings in said head communicating with saidpassage for directing flame against the interior surface of said boreincluded within a short cylindrical zone; a cooling medium space in saidhead surrounding said gas passage; one set of spray openingscommunicating with said medium space for directing a cooling mediumtherefrom against said surface and about the entire periphery thereofimmediately behind said flame to quench and harden said surface after itis heated; and another set of spray openings also communicating withsaid medium space for directing said cocling medium therefrom againstsaid surface and about the entire periphery thereof immediately inadvance of said flame to prevent preheating thereof until said flame isbrought into contact therewith.

6. In a burner for use in flame hardening the interior of bores, thecombination of: a head insertable in said bore for advancing movementlongitudinally therethrough; a gas passage in said head; a plurality ofradially disposed burner openings in said head communicating with saidpassage for directing flame against the interior surface of said boreincluded within a short cylindrical zone; a liquid space in said headsurrounding said gas passage; one set of spray openings disposed behindsaid burner openings communicating with said liquid space and directedrearwardly of said' flame openings for directing a cooling mediumtherefrom against said interior surface rearwardly of the advancingflame to quench and harden said interior surface after it is heated; andanother set of spray openings also disposed behind said burner openingscommunicating with said liquid space and-directed forwardly of saidflame openings for directing said cooling medium therefrom against saidinterior surface in advance of said flame to prevent pre-heating of thesurface until said flame is brought into contact therewith.

7. In a burner for use in flame hardening the interior of bores, thecombination of: a head insertable in said bore for advancing movementlongitudinally therethrough; a gas passage in said head; a plurality ofradially disposed burner openings in said head communicating with saidpassage for directing flame against the interior surface of said boreincluded within a, short cylindrical zone; a liquid space in said headsurrounding said gas passage; one set of spray openings disposed behindsaid burner openings communicating with said liquid space and directedat an angle rearwardly of said burner openings for directing a coolingmedium therefrom against saidinterior surface rearwardly of theadvancing flame to quench and harden said interior surface after it isheated; and another set of spray openings also disposed behind saidburner openings communicating with said liquid space and directed at anangle forwardly of and'between adjacent ones of said burner openings fordirectstantially radially extending gas openings com-' municating withsaid gas passage near the.opposite end thereof; plug means in saidopposite end having means thereon projected into said gas passage torestrict the passage adjacent said openings for producing a uniform flowof gas therefrom; a cooling medium conduit surrounding said gas conduitand coupled to said body to pass a cooling medium about said gas'conduitand-into the interior of said burner body; and a plurality ofcircumferentially spaced spray openings extending outwardly through saidbody for thepassage of cooling medium, a part of said spray openingsbeing spaced in staggered relation to the spacing of the gas openingsand directed forwardly therebetween, the remainder of said sprayopenings being directed rearwardly.

FRANK C. EMERY. EDWIN F. GREEN.

